#define _CRT_SECURE_NO_WARNINGS
#include<stdio.h>

int main()
{
    //int a = 0;
    //int b = 0;
    //int c = 0;
    //int d = 0;
    //int e = 0;
    //scanf("%d %d %d %d %d", &a, &b, &c, &d, &e);
    //printf("%.1f\n", (a + b + c + d + e) / 5.0);
        int s = 0;
        int i = 0;
        int sum = 0;
        for (i = 0;i < 5;i++)
        {
            scanf("%d", &s);
            sum += s;
        }
        printf("%.1f", sum / 5.0);
    return 0;
 }

	